The present applicant has proposed a connection device which integrally connects fluid pressure devices such as a filter, a regulator, and a lubricator, which are used in a pneumatic circuit (see Japanese Patent No. 3851119). This connection device employs a structure in which a through hole is formed in a body having a hole part, an engaging member is engaged with a bolt which is inserted through the through hole, an engaging flange of the engaging member is engaged with each protrusion part provided in the vicinity of a port of two adjacent fluid pressure devices, and then the bolt is fastened so as to connect the fluid pressure devices with each other via the engaging flange.
Further, the present applicant has proposed an invention related to the connection device: “connection structure for fluid pressure devices” in which the structure is further simplified and which is suitable for downsizing (see Japanese Patent No. 5565634).